Apparatus for coating containers



aearcn WOO" Jan. 30, 1945. v. A. FOX

APPARATUS FOR comma cormmsas Filed Dec. 19, 1941 4 Sheets-Sheet l.frzverar Ernie a. fix

Jan. 30, 1945. v. A. FOX

APPARATUS FOR COATING CONTAINERS Filed Dec. 19, 1941 4 Sheets-Sheet 2fnvent ar .VG-TVZL'G Q. fax if Z Jan. 30, 1945. 2,368,130

V. A. FOX

APPARATUS FOR COATING CONTAINERS Filed D60. 19, 1941 4 She'ets-Sheet 3mwbg 4 Sheets-Sheet 4 V. A. FOX

APPARATUS I'OR COATING CONTAINERS Filed D60. 19, 1941 Jan. 30, 1945.

Patented Jan. 30, 1945 OCGHJII "UUli UNITED STATES PATENT OFFICEAPPARATUS FOR COATING CONTAINERS setts Application December 19, 1941,Serial No. 423,628

6 Claims.

This invention relates to the coating of containers and moreparticularly to an improved apparatus for coating containers having oneclosed end and one end with a relatively large opening therein.

Many methods and machines have been devised heretofore for the purposeof coating containers of various kinds by dipping, spraying, flooding,etc., but many of these are adaptable only for coating the exteriorcontainer surfaces, and others have failed to produce an unbroken andsubstantially uniform coating on both the inside and outside of thecontainers being processed because they required that these containersbe firmly held by some sort of clamping device. The failure of the priorart methods and machines to produce a complete film of coating materialover the container has retarded the development of inexpensive packageswhich are resistant to the action of moisture vapor, oil, or othermaterials.

I have devised an improved apparatus whereby a complete and uniformcoating of the desired material can be applied to tubular containers,such as folding cartons adapted to be used for food products and thelike. Many types of coating materials can be used, depending upon thetype of product with which the containers are to be filled, but myinvention is particularly adapted for use in connection with athermoplastic material which imparts unusually high resistance to thepassage of moisture vapor through containers coated therewith, and itwill be described principally in connection with the use of such acoating material.

It is an object of my invention to provide an improved apparatus forapplying a substantially uniform film of a coating material to theinternal and external surfaces of a container, preferably a tubularcontainer formed from a foldable blank, having one of its ends closedand the other open or formed with a relatively large opening therein. Afurther object is to provide apparatus of this type particularly adaptedfor use in connection with thermoplastic coating materials and whichrequires a minimum of floor space. Further objects, advantages and usesof my invention will be apparent from the following detailed descriptionread in conjunction with the drawings, in which:

Fig. 1 shows somewhat schematically a longitudinal cross-section throughone form of coating apparatus according to my invention.

Fig. 2 is an enlarged view illustrating in an exaggerated manner the wayin which any air trapped within the containers during the coatinoperation i prevented from interfering with the production of anunbroken film of coating material.

Fig. 3 shows a side view of one of my preferred forms of containersupports and the manner in which a container rests thereon.

Fig. 4 is a partial cross-sectional view taken along line 4-4 of Fig. 1.

Fig. 5 is a cross-sectional view taken along line 5-5 of Fig. 4.

Fig. 6 is a top view of one of the container supports illustrated inFigs. 3 and 4.

Fig. 7 is a side view of the container support shown in Fig. 6, and

Fig. 8 is a longitudinal cross-section through a modified form ofcoating apparatus embodying my invention, which is similar to that shownin Fig. 1, but omits the pre-heating means.

In one of its broad aspects, my invention comprises introducingcontainers having one closed end and one end with a relatively largeopening therein into a bath of coating material, rotating thesecontainers within the bath from ap proximately horizontal positionthrough an angle substantially greater than about a horizontal axiswhich is substantially perpendicular to the longitudinal axis of thecontainers, the direction of rotation being such that the open end ofeach of these containers passes through and beyond its downwardly facingposition. It will be seen that this results in the trapping of a minimumof air against the closed end of the container and that, if any air isso trapped, it is caused to move from one side of the container to theother, thus allowing the coating material to come in contact with theentire interior surface thereof. My invention can best be understood inall of its details, however, by reference to the drawings which showforms of apparatus suitable for achieving this result including manyother features.

Referring now to Figs. 1, 4 and 5, a pair of endless roller chains Marecaused to move generally upward in parallel paths from a pair ofsprockets l I over a pair of sprockets l2 and then downward around thelower portions of a third pair of sprockets [3 which are located withina receptacle l4 adapted to hold a pool or bath of the desired coatingmaterial. The shaft I5, upon which sprockets iii are mounted, is locatedslightly below the liquid level I6 of the bath, so that chain III arecaused to enter into the bath a substantial distance. It is desirablethat chains It should enter the bath in substantially vertical positionand this is achieved by causing these chains to roll along a pair ofguides ll between sprockets l2 and sprockets l3. Chains l then passupwardly preferably at an angle somewhat less than 90, but greater than45, from the horizontal over a pair of guides l8 which have longsubstantially horizontal portions extending through the heating andcooling chambers to be described below. Chains I then pass over a pairof sprockets I9 which are driven by any suitable means (not shown) andthen back to the lower portion of sprockets ll along a path defined byguides 20 and 2|.

Spaced along the chains are a number of container supporting deviceswhich can best be seen in Figs. 4 and 5. Rigidly fixed to correspondinglinks in the chains H) are inwardly extending arms 22 having holestherethrough into which are inserted the upwardly extending portions ofa U-shaped bar 23, these upwardly extending portions being held in aposition perpendicular to the position of the corresponding links bymeans of nuts 24. One or more rods or spindles 25 are attached bywelding or the like to the horizontal portion of each bar 23, and thesealso are perpendicular to the links of the chains ill with which theyare associated. Each of the spindles 25 has its free end bent insubstantially horizontal position and carries two rod-like members 26extending laterally on either side thereof and bent upwardly at an acuteangle as shown in Fig. 7. The ends of the members 26 are curved so as toprovide rounded surfaces for supporting the containers to be coated, andthe forward ends of each of these members, that is, the ends extendingin the direction of movement, are somewhat more elevated than thefollowing ends, as shown in Figs. 3 and 7, for purposes which will bedescribed below.

It will be seen that this construction allows a number of containers tobe placed on the spindles 25 and that these containers will travelthroughout the length of the apparatus without any clamping action.During the dipping operation it is, of course, essential that thecontainers should be caused to assume the desired positions regardlessof slight variations in air entrapment and this is accomplished bybringing the outer surfaces of their closed ends successively in contactwith guide 21 and then shaft l5. It is desirable that there should beconsiderable freedom of movement of the containers on the supportingmembers 26 so that the area included within the ends of these members ispreferably substantially smaller than the cross-sectional area of thecontainer to be coated. as shown in Fig. 3, for example.

The particular embodiment of my invention shown in Fig. 1 is especiallyadapted for coating containers with a thermoplastic material, such as acomposition containing a major portion of paraflin wax and a minorportion of rubber having a softening point in the neighborhood of120-l40 F. Consequently, the receptacle i4 is equipped with a pluralityof electrical heating elements 28 of the conventional strig type for thepurpose of maintaining the bath of coating material therein at thedesired temperature which may be in the case of the particular coatingmentioned above about 175-185 F. As a further aid in maintaining theproper bath temperature, means are provided for preheating thecontainers to be coated comprising a combustion chamber 29 equipped witha gas burner 30, or the like, a blower 3| for propelling the combustiongases into a second chamber 32 and a foraminous baflie 33 so arrangedthat the hot gases from chamber 32 are directed against the containerson supports 26, as the latter travel upward and then downward intoreceptacle l4.

Somewhat similar means are likewise provided for maintaining the coatedcontainers emerging from the bath at an elevated temperature for aspecified time so as to facilitate draining of the excess coatingmaterial therefrom. The arrangement for accomplishing this consists of asecond combustion chamber 34 containing a burner 35 and a blower 36which directs the combustion gases through chamber 31 and foraminousbaflie 38 against the coated containers as they travel from the bath upto and along a portion of the horizontal section of the conveyingmechanism. The portions of the apparatus just described are preferablyinsulated to avoid undue loss of heat, and the part thereof underlyingthe draining section is inclined at a slight angle toward the receptaclel4, so that this material will flow into the bath for reuse. The coatedcontainers then pass from the draining chamber into a cooling section inwhich they are cooled by means of a blast of air directed throughforaminous baflle 39 by means of blowers 40.

In the operation of this embodiment of my invention, the endless chainsI0 are caused to move throughout the path previously described and thecontainers to be coated are placed by hand or otherwise over thespindles 25 and supports 26 at the point indicated by the arrow 4|.These containers then travel in the position indicated upwardly and thendownwardly into the pool of coating material and are thus preheated bythe hot gases directed through the openings in the baflle 33. Gases ofany desired super-atmospheric temperature may be used, but it ispreferred in general to use temperatures in the range of -175.

As the containers are about to enter the bath of coating material, theirclosed ends strike guide 21 which directs them into the bath with theirclosed ends immediately adjacent shaft l5. The action of this portion ofmy apparatus can best be seen from Fig. 2, to which reference is nowmade. In this figure, the dot-and-dash line represents the projection ofthe path of travel of chains In and the positions of the containersbeing coated are shown for various positions of the spindles 25designated as positions A, B, C, and D.

In position A it will be noted that the guide 21 causes the container tobe raised somewhat from its position on the supports 26, so that theopen end of the container is presented to the surface l6 of the bath andthe coating material can begin to flow into the interior of thecontainer. As spindle 25 travels downwardly, this efiect is accentuateduntil the leading portions of supports 26 are in contact with theleading edge of the container at its closed end and then the containeris forced to travel downwardly until it assumes a position similar toposition B.

In position B a rather large amount of air is shown as being trapped inthe container, but this air will be reduced very considerably oreliminated completely as the spindle 25 continues its movement due tothe fact that the buoyancy of the trapped air will cause the open end ofthe container to swing upwardly and release most, if not all, of thetrapped air. It will also be seen that during this stage, namely, justbefore the container is completely immersed in the bath, itslongitudinal axis assumes a substantial horizontal position. Themovement of spindle 25 from position B to position C is one of rotationas already described and the container necessarily makes substantiallythe same rotation.

In position C the container is shown as having a small amount of airtrapped therein, but it will be noted that the position of this trappedair is such that it comes in contact with the interior of the containeronly at those portions of the surface which have previously been incomplete contact with the coating material, as for instance, in positionB. Consequently, all portions of the interior surfaces as well as theentire external surface of the container is coated. It would be possibleto remove the container from the bath in a position corresponding toposition using some other type of apparatus, since it has been rotatedsubstantially more than 90 and has had an opportunity to becomecompletely coated, but in the preferred form of my invention asillustrated in Figs. 1 and 2, this rotation is continued and finally thespindle 25 assumes position D in which the container has partiallyemerged from the bath. In the present instance, the entire rotation ofthe spindle 25 and, hence, of the container thereon, is approximately150 and it is preferably somewhat less than 180 and more than 135.

When the spindle 25 and the container carried thereby have traveledbeyond position D a sufilcient distance, the opening in the containerwill be above the liquid level l6 and substantially all of the coatingmaterial within the container will drain therefrom. It is preferred,however, to allow a predetermined time for further draining in orderthat the resultant coating may be uniform and of the desired thickness,and the coated containers, therefore, pass through the draining sectionshown in Fig. l and described above, in which they are subjected tostreams of gas at super-atmospheric temperatures, such as 140?- 175" F.During the horizontal portion of their travel through this chamber, thecontainers assume the position shown in Fig. 3 due to the difference inheight between the leading and fol lowing portions of supporting members26 and this facilitates the draining operation. Furthermore. the gasstreams directed through the openings in baffle 38 cause the containersto be blown from side to side and against spindle 25 which also aids inremoving any coating material which i would otherwise accumulate aroundthe lower open end of the container. The containers then pass into thecooling section in which the relatively cool gases directed thereoncause the coating material to dry or otherwise solidify. Finally, as thechains In pass over sprocket IS, the spindles 25 are caused to rotate insuch a way that the cool, completely coated containers fall therefrom bythe action of gravity.

It will be seen from the above description that I have devised animproved method of applying uniform coatings to containers and novelapparatus {or carrying out this method. It is not p essential in allinstances, however, that the containers be preheated prior to thecoating operation, and an apparatus embodying my invention omitting thepre-heating arrangement is illustrated in Fig. 8. This apparatus issimilar to that already described and corresponding reference charactersare used to indicate corresponding parts. Many other modifications can,of course, be made readily by those skilled in the art, falling withinthe scope of my invention.

While I have illustrated my invention in connection with certainspecific embodiments there- Search Roor of, I do not wish to be limitedto such embodiments but only by the scope of the appended claims.

I claim:

1. Apparatus for coating tubular containers having one open and oneclosed end comprising, in combination, a pair o endless chain rnembers,means for causing saidhairr'ih'ribers to move in correspondinghorizontally spaced paths, including a downward followed closely by anupward movement, a-plurality of cross pieces at spaced points along thepath of travel of said chain members, each of said cross pieces beingrigidly secured to one link in each of said chain members, said linksbeing in corresponding positions along said path of travel, at least onecontainer-supporting member rigidly secured adjacent one end to each ofsaid cross pieces with its axis perpendicular to the links associatedtherewith, the free end of said container-supporting member being inupright position during the transition from said downward to said upwardmovement, an d a,receptacleadap@.l9.hold a pool of coating material intowhich containerh placed on said container-supporting means will beimmersed by virtue of said downward and upward movements.

2. Apparatus according to claim 1, wherein said container-supportingmember has a plurality of prongs at the free thereof, those of saidprong in leading position being of greater height than the others.

3. Apparatus according to claim 1 wherein said container-supportingmember comprises an upstanding spindle having a plurality of prongsextending laterally from the free end thereof, the distances between theends of said prongs being substantially less than the correspondingdimensions of the container to be supported thereon, whereby saidcontainer can be easily placed over said spindle with its closed endresting on at least some of said prongs and the points of contactbetween said container and said prongs can shift readily.

4. In apparatus for coating tubular containers having one open and oneclosed end including a chain conveyor, improved means for supportingsaid containers comprising an upstanding spindle mounted on saidconveyor and a plurality of prongs extending laterally from the free endthereof, the more forward of said prongs being of greater height thanthe others and the distances between the ends of said prongs beingsubstantially less than the corresponding dimensions of the container tobe supported thereon, whereby said container can be easily placed oversaid spindle with its closed end resting loosely on at least some ofsaid prongs and will rest with its longitudinal axis at a small acuteangle to said spindle when said spindle is in vertical position.

5. Apparatus for coating tubular container having one open and oneclosed end comprising, in combination, a pair of endless chainconveyors, a receptacle adapted to hold a pool of coating material,means for causing said conveyors to move in corresponding horizontallyspaced paths, said last-mentioned means including a pair of sprocketcoaxially mounted within said receptacle and having said conveyorpassing around the lower portion thereof and subsequent guide means forcausing said conveyors to travel upwardl and then substantiallyhorizontally, a plurality of cross pieces at spaced points along thepath of travel of said conveyors, each of said cross pieces beingrigidly secured one link in each of said conveyors, said links being incorresponding position along said path of travel, at least one spindlerigidly mounted on each of said cross pieces with its axis substantiallyperpendicular to the links associated therewith, each of said spindleshaving a free end extending toward the axis of said sprockets as theirassociated cross pieces pass therearound, and a plurality of prongmembers extending laterally from each of said free ends, the distancesbetween the extremities of said prong members being substantially lessthan the corresponding dimensions of the container to be upportedthereon and those of said prong members extending in the direction ofmotion of said conveyors being of greater height than the others.

6. Apparatu for coating containers having one closed end and one openend comprising, in combination, an endless conveyor, means, for causingsaid conveyor to move in a path including a downward followed closely byan upward movement, a plurality of container-supporting members mountedon said conveyor at intervals along said path of travel, each of saidcontainer-supporting members being rigidly secured adjacent one end tosaid conveyor with its axis substantially perpendicular thereto and thefree end of each of said container-supporting members being in uprightposition during the transition from said downward to said upwardmovement, and a receptacle adapted to hold a pool of coating materialinto which containers placed on said container-supporting means will beimmersed by virtue of said downward and upward movements.

VERNIE A. FOX.

that the said Letters Patent should be re CERTIFICATE OF CORRECTION.

Patent No. 2,558,150. January 0, 191

VERNIE A. FOX.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 5.,secclaim 2, after the word free" insert --end-; end

0nd column, line 50,

ad with this correction therein that the same may conform to the recordof the case in the Patent Office Signed and sealed this 5th day of June,A. b. 191

Leslie Frazer (Sea 1) Acting Commissioner of Patents.

